Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Institute of Medical Virology, University of Zurich, Zurich, Switzerland.
Sci Rep. 2020 Sep 30;10(1):16084. doi: 10.1038/s41598-020-72979-4.
Populations of genetically identical bacteria are phenotypically heterogeneous, giving rise to population functionalities that would not be possible in homogeneous populations. For instance, a proportion of non-dividing bacteria could persist through antibiotic challenges and secure population survival. This heterogeneity can be studied in complex environmental or clinical samples by spreading the bacteria on agar plates and monitoring time to growth resumption in order to infer their metabolic state distribution. We present ColTapp, the Colony Time-lapse application for bacterial colony growth quantification. Its intuitive graphical user interface allows users to analyze time-lapse images of agar plates to monitor size, color and morphology of colonies. Additionally, images at isolated timepoints can be used to estimate lag time. Using ColTapp, we analyze a dataset of Staphylococcus aureus time-lapse images including populations with heterogeneous lag time. Colonies on dense plates reach saturation early, leading to overestimation of lag time from isolated images. We show that this bias can be corrected by taking into account the area available to each colony on the plate. We envision that in clinical settings, improved analysis of colony growth dynamics may help treatment decisions oriented towards personalized antibiotic therapies.
遗传上相同的细菌群体表现出表型异质性，从而产生了在同质群体中不可能出现的群体功能。例如，一定比例的不分裂细菌可以在抗生素的挑战中存活下来，从而确保种群的生存。通过将细菌铺在琼脂平板上，并监测生长恢复的时间，来推断它们的代谢状态分布，可以在复杂的环境或临床样本中研究这种异质性。我们介绍 ColTapp，这是一种用于细菌菌落生长定量的菌落延时应用程序。它直观的图形用户界面允许用户分析琼脂平板的延时图像，以监测菌落的大小、颜色和形态。此外，孤立的时间点的图像可用于估计迟滞时间。使用 ColTapp，我们分析了包括具有异质迟滞时间的金黄色葡萄球菌延时图像数据集。密集平板上的菌落很早就达到饱和，导致从孤立图像中估计的迟滞时间过高。我们表明，可以通过考虑平板上每个菌落可用的面积来纠正这种偏差。我们设想，在临床环境中，改进对菌落生长动态的分析可能有助于做出针对个性化抗生素治疗的治疗决策。
